A severe or chronic total occlusion (CTO) is a vessel blockage that prevents blood flow beyond the occlusion. Chronic total occlusions most often occur in coronary and peripheral arteries and result from atherosclerosis.
A procedure for treating CTOs is percutaneous transluminal angioplasty. During an angioplasty procedure, access to a desired blood vessel is obtained and a guidewire is introduced into the blood vessel. The guidewire is maneuvered into place, including being passed into and through the occlusion, and acts as a guide for positioning a subsequent treatment device used to dilate or otherwise treat the vessel occlusion. The treatment device can be advanced over the guidewire so that its distal portion is positioned within the occlusion. A dilatation balloon at the distal portion of the treatment device can then be inflated to apply radial pressure to the occlusive material and adjacent inner wall portions of the vessel, thereby clearing the occlusion to enable better blood flow.